/**
 *  Copyright (c) 1997-2013, www.tinygroup.org (luo_guo@icloud.com).
 *
 *  Licensed under the GPL, Version 3.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *       http://www.gnu.org/licenses/gpl.html
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package org.tinygroup.springmvc.util;

import org.springframework.util.ObjectUtils;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.util.WebUtils;
import org.tinygroup.springmvc.http.MediaType;

import javax.servlet.http.HttpServletRequest;
import java.util.Iterator;
import java.util.List;

/**
 * Helper class for annotation-based request mapping. 基于注解的ServletMapping工具类
 * 
 * @since 2.0
 */
public abstract class ServletAnnotationMappingUtils {

	/**
	 * Check whether the given request matches the specified request methods.
	 * 
	 * @param methods
	 *            the HTTP request methods to check against
	 * @param request
	 *            the current HTTP request to check
	 */
	public static boolean checkRequestMethod(RequestMethod[] methods,
			HttpServletRequest request) {
		if (!ObjectUtils.isEmpty(methods)) {
			boolean match = false;
			for (RequestMethod method : methods) {
				if (method.name().equals(request.getMethod())) {
					match = true;
				}
			}
			if (!match) {
				return false;
			}
		}
		return true;
	}

	/**
	 * Check whether the given request matches the specified parameter
	 * conditions.
	 * 
	 * @param params
	 *            the parameter conditions, following
	 *            {@link org.springframework.web.bind.annotation.RequestMapping#params()}
	 * @param request
	 *            the current HTTP request to check
	 */
	public static boolean checkParameters(String[] params,
			HttpServletRequest request) {
		if (!ObjectUtils.isEmpty(params)) {
			for (String param : params) {
				int separator = param.indexOf('=');
				if (separator == -1) {
					if (param.startsWith("!")) {
						if (WebUtils.hasSubmitParameter(request,
								param.substring(1))) {
							return false;
						}
					} else if (!WebUtils.hasSubmitParameter(request, param)) {
						return false;
					}
				} else {
					String key = param.substring(0, separator);
					String value = param.substring(separator + 1);
					if (!value.equals(request.getParameter(key))) {
						return false;
					}
				}
			}
		}
		return true;
	}

	/**
	 * Check whether the given request matches the specified header conditions.
	 * 
	 * @param headers
	 *            the header conditions, following
	 *            {@link org.springframework.web.bind.annotation.RequestMapping#headers()
	 *            RequestMapping.headers()}
	 * @param request
	 *            the current HTTP request to check
	 */
	public static boolean checkHeaders(String[] headers,
			HttpServletRequest request) {
		if (!ObjectUtils.isEmpty(headers)) {
			for (String header : headers) {
				int separator = header.indexOf('=');
				if (separator == -1) {
					if (header.startsWith("!")) {
						if (request.getHeader(header.substring(1)) != null) {
							return false;
						}
					} else if (request.getHeader(header) == null) {
						return false;
					}
				} else {
					boolean negated = (separator > 0 && header
							.charAt(separator - 1) == '!');
					String key = !negated ? header.substring(0, separator)
							: header.substring(0, separator - 1);
					String value = header.substring(separator + 1);
					if (isMediaTypeHeader(key)) {
						List<MediaType> requestMediaTypes = MediaType
								.parseMediaTypes(request.getHeader(key));
						List<MediaType> valueMediaTypes = MediaType
								.parseMediaTypes(value);
						boolean found = false;
						for (Iterator<MediaType> valIter = valueMediaTypes
								.iterator(); valIter.hasNext() && !found;) {
							MediaType valueMediaType = valIter.next();
							for (Iterator<MediaType> reqIter = requestMediaTypes
									.iterator(); reqIter.hasNext() && !found;) {
								MediaType requestMediaType = reqIter.next();
								if (valueMediaType.includes(requestMediaType)) {
									found = true;
								}
							}

						}
						if (negated) {
							found = !found;
						}
						if (!found) {
							return false;
						}
					} else {
						boolean match = value.equals(request.getHeader(key));
						if (negated) {
							match = !match;
						}
						if (!match) {
							return false;
						}
					}
				}
			}
		}
		return true;
	}

	private static boolean isMediaTypeHeader(String headerName) {
		return "Accept".equalsIgnoreCase(headerName)
				|| "Content-Type".equalsIgnoreCase(headerName);
	}
}
